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    <title>Document</title>
    <script>
        var i = prompt("今天是星期二，请输入一个天数","1000")
        var j = i % 7;
        if (j = 0) {
            alert (i + "天后是星期二" )
        } else if (j = 1) {
            alert (i + "天后是星期三")
        } else if (j = 2) {
            alert (i + "天后是星期四")
        } else if (j = 3) {
            alert (i + "天后是星期五")
        } else if (j = 4) {
            alert (i + "天后是星期六")
        } else if (j = 5) {
            alert (i + "天后是星期日")
        } else if (j = 6) {
            alert (i + "天后是星期一")
        }
    </script>
</head>
<body>
    
</body>
</html>